1. Field of the Invention
The present invention relates to solid-state image pickup devices and driving methods for solid-state image pickup devices, and more particularly, to horizontal-scanning solid-state image pickup devices and driving methods for horizontal-scanning solid-state image pickup devices.
2. Description of the Related Art
In camera modules, such as digital still cameras, using a solid-state image pickup device, for example, in contrast with a still image mode in which information of all pixels of the solid-state image pickup device is used, the resolution is reduced by adding pixel information or by skipping pixel information in a monitor mode in which an object is monitored. Accordingly, in a solid-state image pickup device for reading pixel information at a low resolution, pixel information of a plurality of pixels in the horizontal direction (lateral direction) in a horizontal signal line has been added by activating horizontal scanning pulses φH for a plurality of columns at the same time using a horizontal scanning circuit and by accessing the plurality of columns at the same time. (See, for example, Japanese Unexamined Patent Application Publication No. 11-146278.)
However, since the solid-state image pickup device according to the known example has an arrangement in which pixels in the horizontal direction are added, if this solid-state image pickup device is used as an image pickup device of a digital still camera, this arrangement cannot be applied to a monitor mode in which pixel addition in the vertical direction (longitudinal direction) is also required. In addition, since pixel information must be read for each row through a horizontal signal line, this arrangement cannot cope with an increase in the speed of reading all pixels in the still image mode.